The use of alcohol (most notably methanol and ethanol) as an automotive fuel dates far back to those simpler days of acetylene lamps and rumble seats when automobile owners were inclined to put anything that was flammable into their fuel tank. However, while alcohol was in many ways a superior fuel to the low-grade gasoline available in the early days, automotive and petroleum refining science progressed to where gasoline became the better fuel, and the use of alcohol fuel in the United States steadily declined. Nevertheless, other countries have not always enjoyed the ready availability of gasoline, and alcohol has at various times found widespread use as a fuel. For example, during World War II, alcohol was the dominant fuel in Europe, and continues to find widespread use in Brazil and other places.
With today's increased concern about the availability of petroleum, the use of alcohol fuel has once more become a topic of pressing interest. Moreover, alcohol has certain desirable attributes that render it an intrinsically desirable fuel. For example, alcohol burns more cleanly than gasoline, the emissions from an alcohol engine being characterized by lower levels of carbon monoxide and nitrogen oxide. Also, alcohol is less explosive than gasoline, and is thus a safer fuel to use. Moreover, alcohol can be made from coal and biomass sources, and is thus, in effect, a renewable resource whereas gasoline (or any petroleum-based fuel) is non-renewable.
One should not, however, be swept away on a wave of euphoria brought about by contemplating the political, economic, and social benefits of alcohol fuel, but rather should be sobered by the recognition that alcohol fuel has its problems. For example, methanol and ethanol are characterized by a considerably lower power output per unit volume than gasoline, and are harder to vaporize than gasoline. While these problems may be overcome to some degree by using a mixture of gasoline and alcohol, commonly referred to as "gasohol," the alcohol must be high proof (190 or above) and the mixture cannot contain more than about 10% alcohol. Therefore, the use of gasohol can only reduce petroleum consumption by a relatively small proportion, and provides little in the way of cost savings.
Thus, while the use of straight alcohol as a fuel is potentially attractive, it will be appreciated that a standard automobile will either run poorly, or not at all, if the fuel tank is merely filled with alcohol, and some sort of retrofitting operation is necessary to adapt existing engines for alcohol use. This tends to be complex and expensive. For example, a generally accepted way of retrofitting a vehicle engine for alcohol use is to provide fuel injection at the cylinders. For the vast majority of engines having carburetors rather than fuel injectors, this requires a new intake manifold. At the same time, an overriding constraint on any retrofitting activity is the requirement that none of the pollution control equipment be disabled or otherwise modified.
A further problem with the use of alcohol as a fuel is its limited availability. There is no doubt that the technology exists to produce alcohol fuel that is cost competitive with gasoline, but there is little incentive to do so unless a large number of vehicles are capable of using the alcohol as fuel. At the same time, there is little incentive to configure automotive fuel systems for alcohol fuel in the absence of abundant supplies of alcohol fuel.
Accordingly, there is presented the need for a retrofit system that renders a vehicle engine capable of running on alcohol fuel. Given that alcohol fuel is not yet readily available in all places, an engine so retrofitted must still be capable of using more conventional fuels.